Generally, in the electronic component mounting apparatus, with a large number of component feed means set in parallel on a component feed table, the component feed means are set to a specified component feed position one by one according to the order of components to be mounted in mounting the components, while the component feed tables are moved in the directions in which the component feed means are arrayed in parallel. Then, the components of the component feed means are sucked up and taken out by a mounting head section, and further transferred and mounted onto a circuit board positioned to a circuit board positioning section.
A conventional component mounting apparatus of this type is described with reference to FIG. 8, which shows a perspective view of the apparatus, and FIG. 9, which shows a schematic plan view thereof. Referring to FIG. 8, at the front of an apparatus body 1 is disposed a board positioning means 4 for positioning to a mounting position a circuit board P which is fed from a board feed means 2. The circuit board P, on which required components have been mounted at the board positioning section 4, will be discharged by a board discharge means 3. On the other hand, at the rear of the apparatus body 1 is disposed a component feed means 7. Between the component feed section 7 and the board positioning section 4, as shown in FIG. 9, is disposed a mounting head section 8 of the rotary type.
In the component feed section 7, two component feed tables 10, 11 are provided so as to be movable rightward and leftward on a guide rail 9 independently of each other. On the component feed tables 10, 11, a multiplicity of component feed units 12 as component feed means are set in parallel along a direction in which the component feed tables 10, 11 move. The component feed units 12 are exemplified in the figure by one which is generally so called parts cassettes, and described in brief below. That is, electronic components of a kind are accommodated on a carrier tape with equal intervals and wound around a reel 13 in a state that the components are covered with a cover tape. The carrier tape is unreeled from the reel 13 and fed at a pitch equal to the interval at which the components are accommodated. Further, the cover tape is wound up, by which the front-end electronic component is positioned to a component feed position A facing one of component suck-up heads 14 of the mounting head section 8.
As shown in FIG. 9, the mounting head section 8 comprises a plurality of component suck-up heads 14 provided at equal angular intervals on the same circumference of a turntable (not shown) provided rotatable about a vertical axis. Each of the component suck-up heads 14 is designed to suck up a component with evacuation means. With the turntable intermittently rotated, each of the component suck-up heads 14 is stopped at the component feed position A and a component placement position B in turn, where the reception of components from the component feed units 12 and the placement of components onto the circuit board P are carried out concurrently. Also, while one component feed table 10 is feeding a component, the other component feed table 11 retreated in the standby position performs the exchange of the component feed units 12 and the replenishment of components, thus making preparations so that the component mounting apparatus is enabled to operate without rest.
However, in the above component mounting apparatus, a board transfer mechanism section comprising the board feed means 2, the board positioning means 4, and the board discharge means 3 is placed on the front side of the apparatus body 1, and the component feed section 7 is disposed rearward of the board transfer mechanism section. As a result, the component mounting apparatus has a defect that it cannot easily accomplish the exchange of the component feed units 12. In more detail, this type of component mounting apparatus would necessarily be installed in such a way that the rear-side component feed section 7, which hardly needs to be accessed except for the component exchange process, is placed as close to the wall surface as possible because of the need of enhancing the use efficiency of the floor space. Accordingly, the work of exchanging the component feed units 12 would necessarily be done in a poor-workability posture in a small space, often taking much labor. Furthermore, since the exchange of component feed units is done with component feed tables located in the component feed path, there is a need of taking care of safety for workers.
Meanwhile, in recent years, there has been a tendency that the number of kinds of circuit boards to be produced as well as the number of kinds of components to be mounted onto the boards are on the increase. On the other hand, when components set on both of the two component feed tables 10, 11 are fed to circuit boards P of the same kind, it would be impossible to change the arrangement for the next model during the mounting process, which would result in a lowered availability factor of the system. This may lead to an idea of increasing the number of component feed units 12 to be set on the component feed tables 10, 11. In such a case, however, the length of the whole component feed section 7 would become significantly longer, not only resulting in a deterioration of the use efficiency of the space, which in turn would cause the productivity per floor area to lower, but also causing the weights of the feed tables 10, 11 to increase, which in turn would necessitate larger driving force for their movements. Moreover, vibrations due to the movement and stop of the feed tables 10, 11 would increase, such that any the operating speed could not be enhanced. Still further, an increased length of the whole component feed section 7 would make it more difficult to exchange the component feed units 12.